Traditionally, “freezing” means that the system doesn’t respond at all. More than likely, your system is just swapping heavily and slowing down to a crawl. If that’s what’s happening, the hard drive activity light will be on constantly.

The best fix for this is more memory, but RAM is currently expensive. If you can’t afford to buy more, you may have to try to cope in software. First, do The Bleeding Obvious: close any programs that you don’t immediately need before you start that Discord call. This includes not leaving unnecessary webpages open, just in case.

See what your distro has to say about swappiness and how to set it. You probably want a value lower than the default 60, maybe even as low as 0.

If it gets worse over tme, it’s possible that something you’re running has a memory leak. You may be able to figure out what using top or similar and seeing which programs’ memory use grows over time. Restarting the greedy ones periodically may be able to keep your system from bogging down, at the cost of some inconvenience.

Moving to a bare compositor rather than the relatively heavyweight KDE might also free up some RAM, but I’m not sure how much that will actually help.